That said, I agree with this 100%:
Allyn Gibson wrote:
The problem, as I see it, is that RTD didn't understand why Children of Earth worked, so when he was asked to do something like CoE but bigger, he didn't know how to do it.
From the little that The Writer's Tale (second edition) covers the writing of Children of Earth, it's clear that CoE was a happy accident that worked in spite of RTD (who didn't have a clear vision of what he wanted to do and didn't understand how the story would work) and not because of him. Which is kind of ironic, in that I believe that CoE is the best thing RTD ever did in the Whoniverse and outclasses anything he did on the mothership.
So I think with Miracle Day he was trying to emulate CoE's success without understanding why it was successful.
A LOT of people here and elsewhere have said the primary problem is 10 eps instead of 5 and it would've been a great story if only shortened. No, I can't agree with that at all. Miracle Day was rotten to the core for precisely the reason said above. There WAS a lot of filler, of course, but that's a superficial, surface issue; this wasn't a Dance with Dragons situation where filler is the problem in a book otherwise incredible. At the end of the day, 10 eps or 5, it still ends with Jack's blood going into a giant vagina and the villains not explained at all, but given a "Bwahaha, next time'll be even more epic" cliffhanger.
No, as Allyn said, the number one problem was that RTD didn't know why CoE had such an effect on people. To someone like me, it's clear what made CoE special was from about the middle of Episode 3 on, when the story becomes about hard moral issues being placed upon us in every day life. This is almost completely ignored in Miracle Day where everyone who works at the cremation centers are would-be rapists or cackling as they make joins about burning Gwen's dad, and the decision to include a child murderer as main character (a very interesting choice) is done as blandly and predictably as possible with him pretending to repent in public then meeting with Jack in private and talking about how he's gonna play this town like a harp from hell Penguin-style or something.
RTD must've thought it was CoE Episode 2/early Ep 3 stuff, where it's all about the government hunting down Torchwood on the run and decided that's primarily what MD would be, and that's what needed to be replicated. But even that wouldn't have been so bad if they had pulled it off more competently, but Miracle Day's attempts to do so just felt like a really flaccid, untense version of 24, made by people who had no idea how to do a convincing political thriller so you just get a lot of political thriller cliches ("Actually, the secret thing you need to know is-" *gets shot*) mixed in with the things they've done elsewhere and better. The villains are an attempt to be a powerful, shadowy cabal, itself a cliche, but one so vaguely and cryptically explained (and then ultimately not explained or dealt with at all) that there's no actual menace to them, as opposed to the all too human Prime Minister from CoE or genuinely alien motivations of the 456. The whole thing just reeks of incompetence and ineptitude.
The concept of a world without death is an interesting enough premise to sustain years worth of stories in any number of medium. But RTD and Jane Espensen trying to emulate 24 was never going to be a great version of that story, not in ten episodes, not in five.